If a great play receives a great adaptation, complete with a great score, can the resulting musical be less than great? Yes, at least if the play is Sean O’Casey’s Juno and the Paycock and its musical version is Juno. City Center Encores! is presenting the Joseph Stein-Marc Blitzstein tuner through this weekend in a concert production starkly directed by Garry Hynes, and doing New Yorkers a great service by exposing them to a beautifully sung performance of Blitzstein’s score.

Even in this trimmed-down version, however, Juno does no similar favors to O’Casey. For while Blitzstein’s songs jig, waltz, celebrate, and sear, they can only do so much to elevate a play that’s determined not to sing.

O’Casey’s original, set during the Irish Civil War of 1922, is a bleak and unyielding journey to the outer reaches of despair, in which the Boyle family of Dublin is ripped apart much as the culture around them is. Though Stein’s book for the musical maintains most of the play’s tragic overtones, it’s set a bit earlier, a lot safer, and considerably more brightly, which make it both more-accessible and less-devastating drama.

Juno Boyle (a smoldering Victoria Clark) sings not only of her weary lot as mother, but trades quips with her do-nothing husband Jack (Conrad John Schuck) as if she’s passing the salt for the meat. She also leads a sing-along in rapture of the sizeable inheritance a relative has apparently left the family, and duets on a touching “madrigally” with her stubborn daughter Mary (Celia Keenan-Bolger).

Clarke Thorell and Celia Keenan-Bolger.Photo by Joan Marcus.

Abrasive, brash, or lyrical as these songs may be, as likely to recall street chanteys as they are grand opera or Kurt Weill, not one directly musicalizes the bloodiest conflicts at the story’s core. Mary’s implosive love life, lodged between the sweet boy (Michael Arden) she doesn’t care at all for and the charming out-of-town lawyer (Clarke Thorell) seeing to Jack’s money, is particularized only by generic (if lovely) ballads that barely touch on the darker issues at play.

More central, but hardly better defined, is the story of her brother, Johnny (Tyler Hanes). A member of the Irish Republican Army under suspicion for bringing about a comrade’s death, Johnny is musicalized mostly in abstract ways (he does not sing) until his responsibility-driven rage explodes into a ballet in the second act. The emotionally expansive “The Ballad of Johnny Boyle,” simply but vividly choreographed by Warren Carlyle, powerfully summons to the surface the nightmarish fantasies and fears that fuel the guilt-riddled Johnny through his tortured existence.

The ballet also represents the only time this musical goes somewhere its source play cannot, which is why it succeeds when so much of the rest of Juno fails. If Blitzstein captures the tense excitement of the Dublin tenements in many of his songs, even those with at best a tangential relationship to the plot (there are far too many numbers for a quartet of busybody women), too many are either unnecessary or witheringly conventional when more acidic specificity would be ideal.

But with Hynes’s take-no-prisoners staging, which keeps the specter of violence always at the forefront; Eric Stern leading the sumptuous, 30-piece Encores! Orchestra and this superlative cast, reservations melt away almost as soon as they form.

Clark’s put-upon, burnt-out Juno all but reeks of the smoke and refuse of her life, but is nonetheless blessed with a well-honed wit that proves how she preserves her sanity in these maddening conditions. Schuck is the comic epitome of gruff laziness, just right for Jack and convincingly challenged by the headstrong woman he must face down at every opportunity.

Keenan-Bolger brings an appealing steadfast innocence to Mary, though her highest notes ring slightly on the shrill side. Arden and Thorell make appropriately endearing suitors for her, while Dermot Crowley makes a thoughtfully funny drinking and carousing buddy for Jack. Hanes’s line readings are occasionally on the harsh side, but his acting and dancing during his ballet are exquisite.

Members of the ensemble stand out as well, with J. Maxwell Miller and Kevin Vortmann unleashing some astonishing vocals during the second act’s lengthy opening scene. Whether they need to in their respective roles as ghostly figures charging a gramophone and Johnny’s most malevolent demons is another issue altogether. But under the Encores! circumstances, it’s worthwhile to give them the benefit of the doubt - this is a score worth savoring even if the show containing it has little unique flavor of its own.